An Analysis of the Greenhouse Gas Emissions by the Re-Liquefaction of Boil-Off Gas of LNG Storage Tank

Gang Sun¹, Shengchun Liu^2*, Xueqiang Li²

¹China Aviation Planning and Construction Development Co., Ltd., Beijing, China.
²Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin, China.

DOI: 10.4236/epe.2015.78033                

Abstract

The pressure in liquefied natural gas (LNG) storage tank continues to increase due to the heat transfer from ambient air to low temperature LNG, which raises safety concerns. Accordingly, there is increasing interest to explore the technical approaches capable of recovering Boil-Off Gas (BOG) and even eliminating the ventilation of LNG storage tank. This research numerically analyzed the greenhouse gas emissions of the re-liquefaction of BOG using the following four approaches: 1) a Claude cycle driven by electrical motor with the electricity produced by burning coal; 2) a Claude cycle driven by a gas turbine fuelled by BOG released; 3) a Claude cycle driven by a SI engine fuelled by gasoline; 4) burning nature gas directly released by BOG. The impact of heat transfer coefficient, LNG tank configuration, size, and percentage of LNG stored in tank on the rate of BOG and energy needed for the re-liquefaction of methane vapor were investigated. The greenhouse gas emissions (GGE) was examined and compared. The data presented in this paper provide guideline for the management of pressure development in LNG storage tank.

Keywords

LNG, Boil-Off Gas, Re-Liquiefication, Greenhouse Gas Emissions

Conflicts of Interest

The authors declare no conflicts of interest.

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